up Inquisit Language Reference

stimulustimes attribute

The stimulustimes attribute specifies the stimulus presentation sequence for a trial in terms of time in milliseconds.

Member of

<likert> <openended> <trial>

Syntax

/ stimulustimes = [time = stimulusname, stimulusname, ...; time = stimulusname, ...]

or

/ stimulustimes = [time = list.name]

or

/ stimulustimes = [time = selectionmode(stimulusname, stimulusname, stimulusname, ...)]

Parameters

time A non-negative integer specifying the time in milliseconds relative to the beginning of the sequence.
stimulusname The name of a stimulus defined elsewhere in the script to be presented on the specified frame.
list.name The name of a list that selects the stimulus to be presented on the specified frame.
selectionmode One of the following values:
Value Description
noreplace Randomly selects without replacement which stimulus in the group to run.
noreplacenorepeat Randomly selects which stimulus in the group to present without replacement and without selecting any single stimulus consecutively.
replace Randomly selects with replacement which stimulus in the group to run.
replacenorepeat Randomly selects which stimulus in the group to present with replacement and without selecting any single stimulus consecutively.
sequence Runs each stimulus in the group.

Remarks

Given that digital monitors repaint the screen with a finite frequency (typically every 10 to 16.7 milliseconds), stimuli can only be physically presented on the display at the particular time the frame is repainted. Inquisit therefore rounds each specified time value to the nearest retrace frame boundary. For example, on a 60 hz monitor, a stimulus time of 3 would be rounded down to 0, a stimulustime of 10 ms would be rounded up to 16.7 ms, and 36 ms would be rounded down to 33.3 ms in order to coordinate the times with the onset of the frame. Multiple stimuli can be assigned to a single time, in which case all of those stimuli are displayed simultaneouly at the given time.

Alternatively, stimulus presentation can be defined in terms of vertical retrace frames using stimulusframes.

Examples

The following trial presents a forward and backward masked prime for 10 milliseconds, and then presens a target stimulus that remains on the screen until the subject responds. Both masks are presented for 20 milliseconds.

<trial mytrial>
/stimulustimes=[0=forwardmask; 20=prime; 30=backwardmask; 50=target]
/ validresponse=("a", "b")
/ correctresponse=("a")
</trial>

The following trial presents a forward and backward masked prime for 10 milliseconds, and then presents a target stimulus that remains on the screen until the subject responds. The particular forward and backward mask used on each trial are selected from list elements named forwardmaskselector and backwardmaskselector respectively:

<trial mytrial>
/stimulustimes=[0=list.forwardmaskselector; 20=prime; 30=list.backwardmaskselector; 40=target]
/ validresponse=("a", "b")
/ correctresponse=("a")
</trial>

The following trial presents a focusstimulus for 500 milliseconds, then presents a two stimuli simultaneously on the left and right of the screen:

<trial mytrial>
/stimulustimes=[0=focusstimulus; 500=lefttarget,righttarget]
/ validresponse=("a", "b")
/ correctresponse=("a")
</trial>

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